Repeat concussion has been associated with risk for prolonged and pronounced
clinical recovery in athletes. In this study of adolescent athletes, we examined
whether an additional head impact within 24 h of a sports-related concussion
(SRC) is associated with higher symptom burden and prolonged clinical recovery
compared with a single-injury group. Forty-two student-athletes (52% male, mean
age = 14.9 years) diagnosed with an SRC in a concussion clinic were selected for
this study: (1) 21 athletes who sustained an additional significant head impact
within 24 h of the initial injury (additional-impact group); (2) 21 single-injury
athletes, age and gender matched, who sustained only one discrete concussive blow
to the head (single-injury group). Groups did not differ on initial injury
characteristics or pre-injury risk factors. The effect of injury status (single-
vs. additional-impact) was examined on athlete- and parent-reported symptom
burden (at first clinic visit) and length of recovery (LOR). Higher symptom
burden was reported by the athletes and parents in the additional-impact group at
the time of first visit. The additional-impact group also had a significantly
longer LOR compared with the single-injury group. These findings provide
preliminary, hypothesis-generating evidence for the importance of immediate
removal from play following an SRC to protect athletes from re-injury, which may
worsen symptoms and prolong recovery. The retrospective study design from a
specialized clinical sample points to the need for future prospective studies of
the relationship between single- and additional-impact injuries on symptom burden
and LOR.